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Full text of "Alaskan glacier studies of the National Geographic Society in the Yakutat Bay, Prince William Sound and lower Copper River regions"

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is no evidence of advance in the Baltimore Glacier, that could be detected by comparison of photographs. There were shrubs at the very edge of the ice, but from our viewpoint at sea level it was impossible to tell whether any had been overridden. Along portions of the margin ice blocks were sliding down the steep slope and across the barren zone. We were inclined to suspect advance in progress in July, 1910, but could not be certain.
Smith Glacier. Smith Glacier, which has a length of about 3$ miles and a width of from 1800 to 3200 feet, is fed by two large and two small tributaries which head in cirques 4000 to 5000 feet above the fiord. The glacier descends at the rate of 2200 feet to the mile and is severely crevassed. The lip of its hanging valley is at a level of 1395 feet, and there are subordinate cascades higher up. There are broad dirt-stained areas on either margin, but no definite lateral moraines. There is a pronounced medial moraine, formed by two lateral moraines uniting at the spur 2387 feet above the fiord, and another from the 3000 foot spur on the east wall. The terminus is a precipitous ice cliff rising about 100 feet above the sea. At sea level just north of the middle of this ice cliff, rock ledges are exposed beneath the glacier.
Gilbert states that in 1899 Smith Glacier reached "the fiord three or four miles from the Radcliffe, and is of the same order of magnitude. Fed by several tributaries among the crests of the range, it gathers in a high mountain valley, and then descends in magnificent cascades down the mountain front to the sea. In the last part of its course it has scarcely any valley, the outer surface of the ice being practically flush with the face of the mountain; and there is no flattening of its profile, as it reaches the water. Though its lower slope is so seamed by crevasses as to exhibit a mere congeries of pinnacles, two lines of medial moraine are distinctly traceable, each partitioning off a fourth part of the ice stream at the side."
This description and the photographs made by the Harriman Expedition, show that Smith Glacier changed very little between 1899 and 1909. One of these photographs (E. H. H., 81) shows a narrow barren zone on each margin of the glacier extending up the mountain slopes to about 1400 feet. In a photograph taken by Grant on July 1,
1909, the same barren zone apparently shows on the north side of the glacier.   In July,
1910, Smith Glacier was actively advancing, apparently having commenced since Grant's visit the year before; and no barren zone was left around its borders.   On the south side at sea level, the glacier had spread to the edge of the barren zone, where, 15 or 20 feet from the glacier, an earlier lateral push moraine crossed a marginal stream, down which small ice fragments were floating.   Higher on the mountain slopes the ice was advancing into the forest and destroying shrubs.
The north side of Smith Glacier had spread farther than the south side, and at the time of our visit was just beginning to destroy the alder along the margin, except at sea level where it was advancing across a narrow zone of bare rock. Along the advancing margin the alders were being destroyed in three ways, by actual overriding of the spreading glacier, by stream encroachment, and by ice-block avalanches which rolled some distance out into the forest (PL CXVI), knocking down and breaking off shrubs and removing their bark 6 or 8 feet above the ground. By the advance a marginal stream had been diverted dome distance northward into the forest.
It was impossible to tell exactly how much the tidal terminus of the glacier had moved forward since 1909 but there was undoubtedly several hundred feet of advance, accompanying the spreading on the north and south margins. Plate CXVII, A, from the north